Investigation of Electroactive Polymers and Other Pretreatments as Replacements for Chromate Conversion Coatings: A Neutral Salt Fog and Electrochemical Impedance Spectroscopy Study

Poly(2,5-bis(N-Methyl-N-Hexylamino)Phenylene Vinylene) (BAM-PPV) as Pretreatment Coating for Aerospace Applications: Laboratory and Field Studies

“…The CCC and primer in the control sample act as a reservoir for mobile Cr(VI), and the high concentration of mobile Cr(VI) allows the chromium based coatings to re-passivate defects in the surface [1,2,3,4]. BAM-PPV also passivates the AA surface, as shown in previous studies, but its duration is limited, due to the lower concentration of sacrificial redox reaction sites, and cannot match the long term corrosion-inhibiting properties of Cr(VI) [1,2,3,4,5,6,21,22,23,24]. …”

“…Poly(2,5-bis( N -methyl- N -hexylamino)phenylene vinylene) (BAM-PPV), Figure 1 , has been examined as a replacement for CCC’s on AA2024-T3 alloys. Neutral salt spray (NSS) exposure testing at the Naval Air Warfare Center Weapons Division (NAWCWD), China Lake, California has shown that BAM-PPV coatings deposited onto AA2024-T3 can prevent corrosion ≥336 h. A DOD CCC replacement requires a minimum of 336 h of NSS exposure testing without evidence of corrosion, blistering or delamination to be considered as an alternative [ 21 , 22 , 23 ].…”

“…Electrochemical impedance spectroscopy (EIS) measurements on the stability of BAM-PPV films at various pH’s (Tris, pH 8.1, and acetate, pH 4.5, buffer solutions) at room temperature showed that BAM-PPV was robust without evidence of delamination or blistering [ 22 , 23 ]. The BAM-PPV films also exhibited purely capacitive behavior with a slightly higher pore resistance ( R po ) than that observed for the bare AA2024-T3 substrate.…”

Smart Inorganic and Organic Pretreatment Coatings for the Inhibition of Corrosion on Metals/Alloys

“…The tetraborate solutions showed improved corrosion resistance with thicker anodic films contaminated with higher concentration of molybdate ions. [102][103][104][105] TCP coatings are formed by solution immersion in a treatment bath composed of hexafluorozirconates, trivalent chromium oxides, chromium sulfate, and fluorborate salts. 87,98-100 Group IV metal coatings require shorter immersion times (≤10 min) and are a potentially green alternative to CCCs.…”

“…170,171 The corrosion protection mechanism for aluminum alloys is still under intense investigation. [178][179][180][181] Researchers at the Naval Air Warfare Center Weapons Division, China Lake, CA synthesized, 182-184 coated, and evaluated a CPs performance both in laboratory 103,185,186 and field testing environments, 187 which was directly compared to CCC. 172 These proposed mechanism(s) are as follows: (1) ennobling of the aluminum alloy, 173 (2) anodic protection/passivation, 174 (3) galvanic and ion-exchange release of oxygen reduction inhibitors, 175 and (4) barrier protection by the reduced form of the CP following an initial galvanic coupling.…”